A bag contains $9$ red balls, $6$ green balls, and $9$ blue balls. If a ball is randomly chosen, what is the probability that it is not blue?
Answer: There are $9 + 6 + 9 = 24$ balls in the bag. There are $9$ blue balls. That means $24 - 9 = 15$ are not blue. The probability is $ \frac{15}{24} = \dfrac{5}{8}$.